The invention relates generally to the field of photovoltaic materials. In particular, the invention relates to a method and apparatus for interconnected photovoltaic cells.
The desire to reduce personal and commercial dependencies on fossil fuel energy sources has been largely responsible for the development of many photovoltaic materials and devices. These developments have also been predicated upon the goal of discovering new environmentally friendly energy sources. Progress and innovation in this field are principally restricted by the costs associated with fabricating photovoltaic devices. The energy and material costs of producing such devices must be recoverable in the electrical energy produced by the device over some reasonable recovery timeframe for the device and its methods of manufacture to be commercially feasible. In addition, the technological feasibility of efficiently manufacturing the devices is a major limiting factor in the field.
When manufacturing photovoltaic modules having a plurality of individually electrically connected photovoltaic cells, the characteristics of the electrical connections between the cells can be a source of economic and technological concerns. Where the surface area of a photovoltaic module is consumed by those regions dedicated to electrically connecting individual photovoltaic cells, the maximum amount of energy per module that can ultimately be produced decreases. In the instance of thin film fabrication techniques, cell interconnections are typically created by a series of connector material deposition and removal steps. Currently utilized techniques, which require cutting into preformed photovoltaic cell regions via laser or mechanical scribes, increase the risk of manufacturing failures and concomitantly drive up costs. Further, using cut outs or selectively depositing and removing material, typically causes substantial material waste. As a result, the energy capturing regions in the photovoltaic device are reduced and the upper boundaries of photovoltaic module performance are limited.
Accordingly, in one embodiment, the invention provides photovoltaic modules with improved cell interconnections, along with methods for reducing manufacturing time and material waste. According to one embodiment, the invention provides a photovoltaic module having a plurality of photovoltaic cells reducing and/or obviating the need for electrical interconnections formed by repeated material removal. In one aspect, the invention provides a photovoltaic module having a plurality of photovoltaic cells disposed between two electrical connection layers. The photovoltaic cells include a photosensitized nanomatrix layer and a charge carrier media. Preferably, the photovoltaic cells also include a catalytic media layer disposed adjacent an electrical connection layer to facilitate charge transfer or current flow from the electrical connection layer to the charge carrier media
In one embodiment, the electrical connection layers interconnect the photovoltaic cells in series. According to one feature, the first electrical connection layer serves as an anode for one group of photovoltaic cells, while also serving as a cathode for another group of photovoltaic cells. In another embodiment, the electrical connection layer interconnects the photovoltaic cells in parallel. In still another embodiment, a portion of the photovoltaic cells are interconnected in series and a portion are interconnected in parallel.
In one embodiment the electrical connection layers include both conductive regions and insulative regions. Preferably, the conductive regions are significantly light transmitting. In various embodiments, the electrical connection layers further include linking-conductor regions. In various versions of these embodiments, the electrical connection layers include groups of significantly light transmitting conductive regions that are electrically connected by light-blocking linking-conductor regions.
According to one feature, the photovoltaic cells of the invention include a photosensitized nanomatrix layer and a charge carrier media. As used herein, the term photosensitized nanomatrix layer includes a photosensitized layer having nanoparticles, a heterojunction composite material, and combinations thereof or the like. In one embodiment, the photosensitized nanomatrix layer includes photosensitized nanoparticles. Preferably, the photosensitized nanomatrix layer includes interconnected titanium dioxide nanoparticles. In another embodiment, the photosensitized nanomatrix layer includes a heterojunction composite material such as, for example, a composite of fullerene in polythiophene.
In another aspect, the invention provides methods of fabricating a photovoltaic module, having a plurality of interconnected photovoltaic cells. Photovoltaic cells amenable to fabrication by the methods of the invention include, but are not limited to, solid state devices, thin film layer devices, Gratzel cells, and dye sensitized nanoparticle devices. In various embodiments, the invention provides methods for fabricating photovoltaic cells on flexible, significantly light transmitting substrates. According to one feature, the methods of the invention also provide for fabrication by a continuous process, such as a roll-to-roll process. As a result, the methods of the invention enable fabrication of photovoltaic cells on a variety of substrate materials, which preferably are flexible at room temperature. Flexible substrates are typically amenable to continuous or semi-continuous manufacturing processes with relatively high throughput rates. As a result according to one embodiment of the invention, manufacturing is performed with relatively inexpensive processing techniques and materials, and finished products are relatively cost-effective and cost-competitive.
In one embodiment, a method for fabricating a plurality of interconnected photovoltaic cells includes: forming a group of photovoltaic cell portions on a first substrate; forming a group of photovoltaic cell portions on a second substrate; and combining the respective substrates and photovoltaic cell portions to form a plurality of interconnected photovoltaic cells.
In another embodiment, the invention provides a method for fabricating a plurality of interconnected photovoltaic cells. In this embodiment, the method includes: forming a group of photovoltaic cell portions on a first portion of a substrate; forming a group of photovoltaic cell portions on a second portion of the substrate; dividing the substrate to separate the first portion from the second portion; and combining the first and second substrate portions to form a plurality of interconnected photovoltaic cells.